High-Performance Match-Action Table Updates from within Programmable Software Data Planes

For long, P4's mantra was that table entries could only be updated by the control plane. With the ongoing Portable NIC Architecture (PNA) standardization efforts, this is changing. In fact, PNA presumably includes explicit methods for table updates from within the data planes. Now, it is onto manufacturers and developers to integrate and use this mechanism in future P4 data planes. This would enable novel and improved applications, e.g., requiring means for maintaining state. We present our implementation of flexible match-action tables for the DPDK-based t4p4s target. We discuss different approaches for table updates from within the data plane and challenges that arise when operating at line rate. Further, we analyze the data consistency of our enhanced table structures in a multi-core scenario and model the memory overhead for state management purposes.